Heated roller blind



Nov. 24, 1953 B0 G. A. sARNO HEATED ROLLER BLIND Filed Aug. 10, 1950 INVENTOR 506.4 See/v0 ATTORNEY BY Z Patented Nov. 24, 1953 HEATED ROLLER BLIND B G. A. Stirnii, S tora Essingen, Stockholm, Swe den, assignor to Allmanna Svenska Elektriska Aktiebola'ge't, Vasteras, Swetl poration en, a Swedish cor- Appli'cation August 10, 1950 SeilalNo. 178,583

Claims primary, application Sweden August 11, 1949 5 Claims.

' Radiators used for the heating of rooms, or the compartments of Vehicles or the like are usually placed under windows, and the temperature of the radiators is comparatively high with respect to the average air temperature in the room, with the result that an upwardly directed air curtain is formed before the window and cannot be pierced by a current of cold-air. During the night, as a rule, a lower temperature of air is preferred and this can be obtained by setting a lower temperature for the radiator. This decrease of temperature, however, has the result that the air curtain can be readily pierced by cold air.

When the heating is effected by the introduction of heated air, the draft becomes still more objectionable. In order to provide a comfort able room; temperature, the overtemperature' of the heated air must be comparatively small with respect to the desired room temperature" and the speed of introduction must be low toavoid the creation of drafts by the heated air itself. Even when the heated air is introduced as an upwardly directed air curtain before the window, the protective action of such air curtain will be only slight and during the night there will be little or no' protective action.

In the compartments of vehicles such as railway cars or aeroplanes the draft conditions with both heating systems become particularly dif ficult due partly to the speed of the vehicle and partly to the difiiculty of maintaining the windows completely airtight as the window-frame is subjected to continuous bending forces during travel.

The present invention has for its object the elimination of the draft from windows and doors. The invention consists in providing a roller blind impervious to light and heated electrically by means of a heating element made of conductive The heating element consists of a sheet of plas tic material which has been made electrically conducting by mixing in carbon black to form I a coherent carbon skeleton. By choosing suitplastic materialinterposed therein. This encloses a comparatively thin air pocket and needs only to be heated to a temperature slightly higher than that of the room to give complete freedom from draft. The blind is suspended from a horizontally mounted curtain-rod and its fixing means can slide on the former. It can be drawn across more or less, and in the daytime freedom from draft may be obtained by allowing one or more of such roller blinds to cover only one part of the window so that light can pass through the uncovered part of the window. The roller blind is mounted so that the free end moves downward as the blind is unrolled.

able qualities of carbon black and suitable quantities thereof, the resistivity of the plastic element may be varied upwardly from at least 10 ohms cm. without loss of flexibility. Fol" heating elements in blinds no plastic material having higher resistivity than 1000 ohms cm. is desirable, and usually a" material is employed having resistivities' between 25 and 100 ohms cm.

The plastic material may consist of such flexible plastics as are flexible and elastic under centigrades and which are able to take up the required quantity of carbon black without losing their flexibility. As it is desirable that the plastic material shall. not support combustion, plastics containing/halogen are employed, such as plastified polyvinyl chloride, plastified copolym'e'riri the molecule chain of which is contained vinyl chloride or vinylidene chloride as a consi'derable component and halogen derivate of polyethylene or the like. Owing to the low temperature of the element, rubber or synthetic rubber may be employed in spite of its inferior aging properties and polymeric chlor butadiene and its co-polymers are preferred in considerationof fire risk. Sun radiation, however, very quickly destroys synthetic rubber and such material, as a rule, is therefore less suitable.

The invention is hereinafter described with reference to the accompanying drawings, where- 1n:

Fig. 1 shows a roller blind according to the invention without insulating coating.

Fig. 2 a cross-section through the roller blind with an; insulating coating on each side.

Fig. 3 shows the lower end of a roller blind insulated on one side only.

Fig. 4 shows the roller blind partly unrolled.

Fig. 5 is a cross-section showing contacting means on the curtain rod for the roller blind, and

Fig. 6 is a longitudinal blind.

The heating element consists of a rectangular sheet of conducting plastic material (I, Fig. l)

' which is made U s'haped by cutting out a slot 3.

The current is supplied to the heating body by means of flexible conductors (2', 2"), located at the two adjacent edges of the legs of the 'U.

This arrangement has the advantage that the section of said rod andvoltage conducting parts can be placed on the upper side of the window, so that there is no danger of the occupants coming into contact with these parts. Another feature of the inven tion is that the slot is used for calibrating the resistivity of the heating body. Prior to the cutting or punching of the slot 3 the resistivity between the current conducting conductors is measured and the width of the slot is so chosen that, after the punching, a resistivity is obtained which corresponds to the desired output.

It is not advisable to arrange the conductors 2', 2" along the vertical edges of the roller blind since the thickening in the blind caused by them would make its rolling more difficult, and for this reason also the position of the conductors as shown is the most favourable. The curtain rod 8 has two electrically insulated contact means separated from each other and placed on each side of the centre line of the curtain rod. The conductors 2', 2' are connected each to its contact means and the current may flow from the free end of the leg through the lower part of the U to the other end of its leg.

The plastic heating element be insulated on both sides by a sheet of insulating plastic material 4, t", for example, as shown in Fig. 2 or on one side only as shown in Fig. If the plastified plastic material is used, the conduct-- ing and the insulating plastic sheets must contain the same quantities and proportions of such plastifiers which can pass iroin one layer to the other. The insulating plastic layers are made somewhat larger than the conducting plastic sheet 4, as shown in Fig. 2, and they may be welded together by means or uency welding to form a pocket enclosing element i. It is even possible to weld the whole surface by passing the roller blind. through rollers between which a radio frequency field is pro vided. Another mode of manufacturing is to press the roller blind between plates, which may be heated or may constitute electrodes for radio frequency heating. The parts may also be connected by means of a suitable adhesive. In order to avoid air enclosures in all cases it is advantageous to evacuate the insulated plastic pocket.

In order to prevent the passage oi light through the slot a ribbon 5 of black plastic material may be inserted in the slot (see Fig. 2) and such material may be coloured by mixing in carbon black in such a concentration that it does not build up a carbon blacl; skeleton and thus does not render the material conductive.

Fig. 4 shows the roller blind partly unrolled. The roller blind i composed of a conducting and an insulating layer rolled about a curtain rod 3 and is reinforced at its lower end by a curtain bar 9 which is held in a channel obtained by folding and weldi g the lower end of the roller blind. In the curtain rod 5% thermostats It may be inserted, and the length of the roller blind is such that, even in its fully unrolled condition, at least one turn of the roller blind remains around the curtain. rod, so that the blind is heated and the thermostats function although the blind is unrolled.

The curtain bar 9 travels within channels ll (see Fig. 4) which prevents that side of the blind which faces the window from being accidentally touched. When low voltage is used, i. e. the voltage of 25-35 volt, it is thus unnecessary to insulate the plastic element on more than one side, as shown in 3. In the curtain rod 8 a groove l4 isformed, as shown in Figs. 5 and 6,

.4 and contact bars H, H" are provided therein. In 6 the rod 9 is shortened and the roller blind is not shown in this figure. The contact H, H" do not extend the entire length of the curtain rod, but are separated by a space a, the width of which is approximately the same as that of the slot 3 (Fig. 1). The other ends of the contact bars make contact with the fittings l3 and the pins [5 at the ends of the curtain rod. The conducting layer l makes contact with the contact bars H, I!" within the said groove l4 and is pressed against these bars by a fixing means which may consist of a bar 10 held in position by means of screws l2 (see Fig. 5). The pins IE on both ends of the curtain rod 8 are connected by some known means with the supply leads l8, l8".

The insulating plastic pocket may be decorated by printing or pattern pressing. It can also be made of plastic material reinforced with textile material. The surface facing the window may be pigmented by aluminum powder, so that a good reflection of the calorific rays of the sun is obtained.

I claim as my invention:

1. An electrically heated roller blind comprising a supporting roller, two electrodes extending longitudinally of the roller and having a central gap between their adjacent ends, a substantially rectangular sheet of comparatively low conductivity and consisting of synthetic resin material with carbon powder mixed therewith to form a coherent skeleton therein, means securing one end of said sheet to the roller with the carbon powder in contact with said electrodes, a centr lly disposed slot formed in said sheet in alignment with said gap and extending from the said end of the sheet to a point spaced from the opposite end of the sheet to give said sheet a U- formation, and a plastic insulating layer adhering to one of the surfaces of said sheet.

2. A heated roller blind according to claim 1, comprising plastic coverings adhering to both surfaces of said sheet.

3. A heated roller blind according to claim 1, comprising a bar secured to the lower edge of the U-shaped sheet and side means for guiding said bar as the blind is raised and lowered.

4. A heated roller blind according to claim 1, comprising a thermostat mounted in said roller in contact with the said sheet, whereby the flow of current though said carbon powder skeleton is controlled.

5. A heated roller blind according to claim 1, comprising a ribbon of plastic material located within and extending the length of said slot to prevent the passage of light therethrough.

BO G. A. sARNo.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,553,461 Negromanti Sept. 15, 1925 1,743,638 Tafit Jan. 14, 1930 2,404,736 Marick July 23, 1946 2,427,502 Marick Sept. 16, 1947 2,469,466 Harrington May 10, 1949 2,473,183 Watson June 14, 1949 2,489,643 Hunter Nov. 29, 1949 2,495,414 Herrington Jan. 24, 1950 2,500,554 MacDonald et al. Mar. 14, 1950 2,548,467 Crise Apr. 10, 1951 2,569,340 same et a1. Sept. 25, 1951 2,575,987 York et al. Nov. 20, 1951 

